A. Field of Invention
This invention pertains to the art of methods and apparatuses for power steering hose designs for performance in high pressure and low to high volumetric expansion environments.
B. Description of the Related Art
Reinforced power steering hose is well known in industry for use in transporting fluids under pressure, particularly in automotive power steering hose applications. These hose assemblies generally comprise a polymeric core hose layer and one or more reinforcing layers formed from strands of fiber or wire material that are braided over the core layer. In most applications, the hose also includes an intermediate hose layer formed over the core hose layer and a first reinforcing layer. A second reinforcing layer is thereafter braided over the intermediate hose layer. Finally, a polymeric cover material is generally formed over the second reinforcing layer to complete the hose assembly.
The reinforcing layers of conventional power steering hose assemblies are generally applied by rotary braiding machines. Using these rotary braiding machines, strands of fiber or wire reinforcing material are wound upon the hose layers in an interwoven, braided pattern. Generally, the rotary braiding machines are configured to provide a braid pattern wherein the strands are successively passed over and under pairs of oppositely wound strands. This is referred to herein as a 2-over, 2-under braid pattern, which can seen in FIGS. 1 and 2. Power steering hoses known in the art utilize the 2-over, 2-under braid pattern in both the first and second reinforcing layers. In certain applications, it may be desired to further improve hose performance by varying the braid patterns, for example, to optimize burst strength, volumetric expansion, impulse life, or coupleability of the hoses.
The present invention provides methods and apparatuses for power steering hose designs for performance in high pressure and low to high volumetric expansion environments. Such power steering hose designs incorporate varying braid patterns in the reinforcement layers.